sysdeps/arm/arm-features.h

   1 /* Macros to test for CPU features on ARM.  Generic ARM version.
   2    Copyright (C) 2012-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _ARM_ARM_FEATURES_H
  20 #define _ARM_ARM_FEATURES_H 1
  21
  22 /* An OS-specific arm-features.h file should define ARM_HAVE_VFP to
  23    an appropriate expression for testing at runtime whether the VFP
  24    hardware is present.  We'll then redefine it to a constant if we
  25    know at compile time that we can assume VFP.  */
  26
  27 #ifndef __SOFTFP__
  28 /* The compiler is generating VFP instructions, so we're already
  29    assuming the hardware exists.  */
  30 # undef ARM_HAVE_VFP
  31 # define ARM_HAVE_VFP   1
  32 #endif
  33
  34 /* An OS-specific arm-features.h file may define ARM_ASSUME_NO_IWMMXT
  35    to indicate at compile time that iWMMXt hardware is never present
  36    at runtime (or that we never care about its state) and so need not
  37    be checked for.  */
  38
  39 /* A more-specific arm-features.h file may define ARM_ALWAYS_BX to indicate
  40    that instructions using pc as a destination register must never be used,
  41    so a "bx" (or "blx") instruction is always required.  */
  42
  43 /* The log2 of the minimum alignment required for an address that
  44    is the target of a computed branch (i.e. a "bx" instruction).
  45    A more-specific arm-features.h file may define this to set a more
  46    stringent requirement.
  47
  48    Using this only makes sense for code in ARM mode (where instructions
  49    always have a fixed size of four bytes), or for Thumb-mode code that is
  50    specifically aligning all the related branch targets to match (since
  51    Thumb instructions might be either two or four bytes).  */
  52 #ifndef ARM_BX_ALIGN_LOG2
  53 # define ARM_BX_ALIGN_LOG2      2
  54 #endif
  55
  56 /* An OS-specific arm-features.h file may define ARM_NO_INDEX_REGISTER to
  57    indicate that the two-register addressing modes must never be used.  */
  58
  59 #endif  /* arm-features.h */